The Java ecosystem has historically used single-dash options, both the SDK tooling (e.g. `java -jar`, `javac -classpath`) and classic common libraries like Jakarta Commons CLI. It has moved away from it more in recent years so now you get a mishmash of single and double dashes depending on how old the option is. In some cases you end up with stuff like `java -showversion` which prints the version to stderr but ` java --show-version` which prints to stdout.